Is the painted surface dusty, as in having a chalky, dusty coating after painting (which can be seen if you run your fingertip over the painted surface) , or is is simply that the paint droplets are inordinately large?

If it's the latter, if I recall correctly, you have a siphon feed 155 and I'm thinking that the 13-15 PSI you are using may not be sufficient for proper paint "draw" from the paint jar and atomisation. Up the pressure to about 18 PSI and see if things improve.

zackesch wrote:

I am using a bader 155. I can see the grain if the painted object is looked at under a bright light. I am using the acryl thinner.

It sounds normal to me. You may want to try enamel paint for comparison. If the enamel also look as grainy, the Badger may need some tuning or fine cleaning.

Don Winter has a comprehensive web pages dedicated to the 155. You can contact him if you have specific questions about the AB. I found it very useful even for an Iwata user.

usmc1371 wrote:

What kind of airbrush are you using?  I've found my Paasche H (external mix) doesn't atomize the MM Acryl paint as well as my A470 (internal mix).

I second what Jesse said. When I upgrade from a Paasche H to an Iwata HP-CS, the internal mix AB offers much finer atomization and the sprayed surface looks smoother. Flat painted surface always feels coarser than gloss paint surface to my finger tip. All should look even to the eye.

In general, acrylic paint also feels coarser in comparison to enemal paint too.

With the Paasche H, the surface looked rougher, more grainy. But it should still be very even when sprayed in multiply light passes. Also, thinning the paint more also reduces the grainyness in dried paint.

What kind of airbrush are you using?  I've found my Paasche H (external mix) doesn't atomize the MM Acryl paint as well as my A470 (internal mix).  Also, are you using the Acryl Thinner or the Acryl Cleaner?  They both come in the same bottle but different lables.  I've confused the two a few times.

-Jesse

If there are small grains showing in the bottle, then no way!!! Something is wrong with the paint.

However, if you mean when it hits the model, its sound like the paint is drying before getting to the model this can happen with acrylics. 

So a couple of question.

How far away from the model are you spray it?

What is your thinner to paint ratio?

MM Acryl can technicaly be painted out of the bottle but I do add a drop or two of their thinner to help with paint flow.

See Ya

Scott